Springer Science and Business Media LLC

The large consumption of coal in cement industry leads to a significant nitrogen oxide (NOx) emission, which has caused severe atmospheric pollution due to the existing low-efficiency denitration technologies. In this research, a fuel pretreatment method on the concept of coal preheating was proposed to reduce NOx emission from cement kilns. A special bench-scale experiment was designed to verify the feasibility of the proposed method. Experimental results showed that the proposed method could achieve high combustion efficiency, steady operation and low NOx emission. The maximum reduction efficiency of primary NO in kiln gas reached 91.4% while the lowest NOx emission was 145 mg/m3 (@10% O2) during the experiment. The effects of key parameters on NOx emission and primary NOx reduction efficiency were comprehensively investigated. It was found that primary and secondary air ratios determined the oxygen content in the flue gas and the reaction temperature, which multiply affected the fuel-NOx formation and activity of reductants. Increasing the length of the reducing zone could not only enhance the primary NOx reduction efficiency, but also lower the combustion efficiency. In addition, cement raw material could greatly accelerate the formation of fuel-NOx while its catalytic action on NOx reduction was limited.

A measurement technique that can measure the concentration of the solid particles in liquid flow was developed. The measurement system consists of a color camera and three LCD displays. The solid particles were put at the bottom of a cylindrical mixing tank in which JetA1 oil was filled. Transient mixing of the solid particles was performed by rotating a propeller type agitator with three different rotation speed (500, 600, 700 r/min). Mixing state was visualized by the LCD displays and a color camcorder. The color intensity of the glass particles changes with their concentration. The color information was decoded into three principle colors R, G, and B so that, the calibration curve of color-to-concentration was performed using these information. A neural network was used for this calibration. The transient concentration field of the solid particles was quantitatively visualized.

A floating type pendulum wave energy converter (FPWEC) with a rotary vane pump as the power take-off system was proposed by Watabe et al. in 1998. They showed that this device had high energy conversion efficiency. In the previous research, the authors conducted 2D wave tank tests in regular waves to evaluate the generating efficiency of FPWEC with a power take-off system composed of pulleys, belts and a generator. As a result, the influence of the electrical load on the generating efficiency was shown. Continuously, the load characteristics of FPWEC are pursued experimentally by using the servo motors to change the damping coefficient in this paper. In a later part of this paper, the motions of the model with the servo motors are compared with that of the case with the same power take-off system as the previous research. From the above experiment, it may be concluded that the maximum primary conversion efficiency is achieved as high as 98% at the optimal load.

The time-dependent variation of airborne particle concentration for different sizes in a test chamber was numerically predicted with drift-flux model. The performance of the drift-flux model for particle transport in different kinds of airflow fields was analyzed. The results show the drift-flux model can predict the transport of indoor fine particles reasonably well. When the air flow field varies slowly, the model can predict both the time-dependent variation ratio of the particle concentration and final stable concentration very well, and the difference for particles with different sizes can be also well predicted. When the air flow varies drastically, the accuracy of the model is decreased due to the neglect of the particles’ independent convective terms in the air flow.

Laser lipolysis can effectively treat obesity and its associated diseases, such as hypertension, fatty liver, and hyperlipidemia. However, currently available invasive laser lipolysis, which transmits laser to a fiber-optic catheter inserted into the subcutaneous tissue for irradiation through an incision, may cause hematomas, infections, and empyrosis. The current study presents a novel, noninvasive approach for laser lipolysis, which directly irradiates the intact skin surface without an incision and preferentially targets adipose tissue at the near-infrared band. High laser energy is necessary to damage adipocytes; however, this may carbonate and burn the dermis. Therefore, the introduction of skin cooling is essential to avoid unwanted hyperthermal injury and improve the threshold of radiant exposure. In the current study, we investigated a novel noninvasive approach assisted with skin cooling by establishing a homogeneous multi-layer skin model. In this method, light propagation in the skin was simulated by using the Monte Carlo method. Skin cooling was employed before laser irradiation to protect the epidermis from thermal damage, which was treated as a boundary condition based on Newton’s law. The numerical results showed that the photons were deposited in the adipose layer more than in the other layers. Laser can effectively destroy adipose tissue at an energy density of >200 J/cm2 at 1210 nm wavelength, whereas at least 300 J/cm2 is required at 1064 nm to achieve the same effect. In this experiment, at >5 s pulse width, the selectivity of adipose was not obvious. Moreover, the results indicated that 60 ms R134a or R404a spray can effectively reduce the temperature of the epidermis. R404a exhibited a stronger cooling effect than R134a. Cold air cooling at −10 °C for 10 s could effectively decrease the skin temperature, and deeper cooling could be achieved by cold air cooling compared with cryogen spray cooling.

Jet impingement boiling has been widely used in industrial facilities as its higher heat transfer coefficient (HTC) and critical heat flux (CHF) can be achieved in comparison with the pool boiling. By covering beads packed porous layer on the heated wall surface, the enlarged heat transfer area and rise of nucleation sites for boiling occur, thus, the heat transfer performance of boiling can be enhanced. For the jet impingement boiling with brass bead packed porous layers, the heat transfer performance is crucially influenced by the characteristics of porous layer and working fluid flow, so the experiments were conducted to investigate the effects of the jet flow rate, fluid inlet subcooling, number of porous layer and brass bead diameter of porous layer. Comparison study shows that impingement boiling promotes the HTC and CHF as 1.5 times and 2.5 times respectively as pool boiling at similar conditions. Higher heat transfer performance can be obtained in the cases of a higher jet flow rate and a higher fluid inlet subcooling, and there exist the optimal layer number and bead diameter for heat transfer. Particularly, a double-layer porous layer results in an increase of 39% in heat flux at superheat of 30 K compared with a single-layer case; a single porous layer at d=8 mm brings an increase of 23% in heat flux at superheat of 30 K compared with that of bare plain surface. Besides, the actual scene of jet impingement boiling was recorded with a camera to investigate the behavior evolution of vapor bubbles which is highly correlated to the heat transfer process.

Through analyzing the motion characteristics of bird-like flapping flight, it is considered that the wing angular acceleration is equal to zero at the point of maximum angular speed. Thus, the flapping flight is equivalent to a uniform rotating motion which can be analyzed by using the stream surface theory of turbomachinery during a micro period of time. In this article, the N-S equations of the motion are expanded in a non-orthogonal curvilinear coordinate system, and simplified on stream surfaces of the flapping flight model. By using stream function method, the three-dimensional unsteady flow equations are simplified as a two-order partial differential equation with variable coefficients eventually and the equation’s iterative solving method on S1 and S2 stream surfaces of the flapping flight model is presented. Through expanding the relatively steady equations of flapping flight at an arbitrary time point of a stroke on meridional plane of the flapping flight model, it can use a relatively steady motion to approximate the real flapping flight at that time point, and analyze the flow stability influenced by the wing’s flexibility. It can be seen that the wing flexibility is related to the higher pressurization capacity and the flow stability, and the pressurization capacity of flexible wing is proportional to the angular speed, angular distortion rate and radius square.

The widespread diffusion of renewable energy sources calls for the development of high-capacity energy storage systems as the A-CAES (Adiabatic Compressed Air Energy Storage) systems. In this framework, low temperature (100°C–200°C) A-CAES (LT-ACAES) systems can assume a key role, avoiding some critical issues connected to the operation of high temperature ones. In this paper, two different LT-ACAES configurations are proposed. The two configurations are characterized by the same turbomachines and compressed air storage section, while differ in the TES section and its integration with the turbomachinery. In particular, the first configuration includes two separated cycles: the working fluid (air) cycle and the heat transfer fluid (HTF) cycle. Several heat exchangers connect the two cycles allowing to recover thermal energy from the compressors and to heat the compressed air at the turbine inlet. Two different HTFs were considered: air (case A) and thermal oil (case B). The second configuration is composed of only one cycle, where the operating fluid and the HTF are the same (air) and the TES section is composed of three different packed-bed thermal storage tanks (case C). The tanks directly recover the heat from the compressors and heat the air at each turbine inlet, avoiding the use of heat exchangers. The LT-ACAES systems were modelled and simulated using the ASPEN-Plus and the MATLAB-Simulink environments. The main aim of this study was the detailed analysis of the reciprocal influence between the turbomachinery and the TES system; furthermore, the performance evaluation of each plant was carried out assuming both on-design and off-design operating conditions. Finally, the different configurations were compared through the main performance parameters, such as the round-trip efficiency. A total power output of around 10 MW was set, leading to a TES tank volume ranging between 500 and 700 m3. The second configuration with three TES systems appears to be the most promising in terms of round-trip efficiency since the energy produced during the discharging phase is greater. In particular, the round-trip efficiency of the LT-ACAES ranges between 0.566 (case A) to 0.674 (case C). Although the second configuration assures the highest performance, the effect of operating at very high pressures inside the tanks should be carefully evaluated in terms of overall costs.